The invention relates to a safety disconnector which serves for disconnecting, in case of need, the electric connection between two conductors. Such devices are used in particular in automotive engineering, e.g. to disconnect the connection to the vehicle battery in an accident so as to de-energize the electric circuits of the vehicle and reduce the danger of explosion. To this end, pyrotechnic disconnectors are known which use a pyrotechnic explosive charge which can be ignited in case of need thus disconnecting the electric connection to the vehicle battery.
It is the object of this invention to provide a disconnector which is less expensive than conventional disconnectors but still has a high degree of reliability.
According to the invention this object is achieved by a disconnector comprising a first conductor, a second conductor which is mechanically connected with the first conductor but electrically insulated therefrom, and a semiconductor switch which provides an electrically switchable electric connection between the first and second conductors. In this way, a disconnector is provided which makes do without complicated and expensive components such as a pyrotechnic explosive charge. On the one hand, the employed semiconductor switch, which may be in particular a transistor, is cost-effective and, on the other hand, it can be arranged with minor expense so as to be protected from the environmental conditions in order to achieve a high degree of reliability.
It is preferably provided that the first conductor has a receiving section which is designed in the form of a pocket and that the second conductor has a holding section which is disposed in the receiving section. This nested arrangement of first conductor and second conductor results in a high mechanical strength.
According to a preferred embodiment an insulating body is provided which is equipped with a mount for the holding section of the second conductor and is disposed within the receiving section of the first conductor. The insulating body, which consists of plastics, for example, ensures the electrical insulation between the first and second conductors, on the one hand, and guarantees the mechanically stable connection between the two conductors, on the other
The insulating body and the receiving section of the first conductor are preferably provided with a recess within which the semiconductor switch is disposed. With this design the semiconductor switch can be disposed in a quasi flush manner, so that it does not protrude beyond the outer surface of the receiving section and thus cannot be damaged.
It is preferably provided that the recess is filled with a sealing compound. Due to the sealing compound the semiconductor switch is protected in optimum fashion from environmental influence, so that the functional reliability of the disconnector is ensured for a long period of time.
The semiconductor switch is preferably in thermal contact with the holding section of the second conductor. The second conductor which with respect to the current to be transmitted by it has a relatively large cross-section, ensures the dissipation of the heat generated when the semiconductor is operated, so that the operating temperature of the semiconductor switch is kept within safe limits.
According to the preferred embodiment it is provided that several shoulders are formed at the edge of the recess of the receiving section of the first conductor and that the semiconductor switch is connected to the first conductor by bond wires which lead to the shoulders. The shoulders enable the bond wires to be guided such that like the semiconductor switch they do not protrude beyond the outer contour of the disconnector. Thus, the bond wires can be fully surrounded by the sealing compound which is disposed in the recess, so that they are protected from damage.
According to the preferred embodiment a connecting plug is provided which has a locking section which extends through the receiving section and the holding section. The connecting plug has a double function: On the one hand, it enables simple connection of a control line with which the semiconductor switch can be signaled. On the other hand, it serves, because of its arrangement, as a mechanical lock which ensures a firm mounting of the components among one another in. particular in the case of tensile or pressure forces acting between the first and second conductors.
It may be provided that the receiving section and the holding section are conically tapered in the mounting direction. The conical shape facilitates the mounting and a tolerance compensation between the receiving section, the holding section and the insulating body.
The receiving section and the support section are preferably provided with mechanical locks. The mechanical locks which may be formed by embossings at the receiving section or noses at the holding section, for example, ensure in the same way as the locking section of the connecting plug a positive engagement between the first conductor, the insulating body and the second conductor, so that the mechanical fit of these components is ensured.
According to a further preferred embodiment of the invention it is provided that the second conductor has a receiving section, that the first conductor has a holding section which is disposed within the receiving section, and that both the receiving section and the holding section have two lateral webs each, which face each other in pairs at a distance and which can be electrically connected to each other by means of several semiconductor switches. In this design, the material cross-section for the current transmission between the two conductors is greater.
It is preferably provided that each lateral web of the receiving section is equipped with terminal lugs one of which is attributed in each case to a semiconductor switch. By using the terminal lugs which extend from the external lateral webs towards the interior of the disconnector, short bond wires can be used so that there is only little danger of mechanical damage.
The semiconductor switches are preferably connected in heat-conducting manner to the lateral webs of the holding section. The large material cross-section of the lateral webs ensures sufficient carrying-off of the resulting power dissipation and prevents inadmissible heat gain of the semiconductor switches.
In order to insulate the semiconductor switches, the space between the semiconductor switches is preferably filled with a sealing compound, and the lateral webs are molded with an electrically insulating material. This material also ensures the insulation between the lateral webs which face each other.
According to a further development the lateral webs are given a structural shape which together with the electrically insulating material ensures a positive engagement between connecting section and holding section. In this way it is possible to transmit reliably tensile forces acting between the first and second conductors, without damaging the disconnector.
According to a preferred embodiment the two lateral webs of the receiving section change into a battery terminal, each lateral web leading to a section of the contact ring of the battery terminal. This design is particularly advantageous because both the receiving section of the disconnector and the contact ring of the battery terminal can be made of a single sheet metal member, e.g. by stamping. Thus, the production cost is low. This design also leads to the fact that the distance between the battery terminal and the disconnector is extremely short, so that when the first conductor is switched off by means of the semiconductor switch there is no more danger that contacting of a live section results in a short circuit between the battery terminal and the disconnector.
Advantageous embodiments of the invention follow from the subclaims.